1. Technical Field
The present invention relates to a light-emitting device, electronic equipment, and a process of producing the light-emitting device.
2. Related Art
Recently, various types of light-emitting devices having light-emitting elements such as organic EL (electroluminescent) elements or organic light-emitting diodes (hereinafter, referred to as “OLEDs”) called light-emitting polymer elements are proposed. The light-emitting elements included in such light-emitting devices usually have a structure in which a light-emitting layer made of an organic EL material is disposed between two electrodes.
For example, Japanese Patent No. 2723242 (Patent Document 1) discloses a light-emitting element composed of an anode, an organic light-emitting medium disposed on the anode, and a cathode disposed on the organic light-emitting medium. In Patent Document 1, a portion of the organic light-emitting medium in contact with the anode functions as a hole-transporting region, and, at the same time, a portion of the organic light-emitting medium in contact with the cathode functions as an electron-transporting region. In addition, in Patent Document 1, the cathode is made of MgAg (magnesium-silver alloy) having a composition of Mg:Ag=10:1.
In a case of a (top emission) configuration in which an anode is disposed on a substrate, an organic light-emitting medium is disposed on the anode, a cathode is disposed on the organic light-emitting medium, and light emitted by the organic light-emitting medium is extracted from the cathode side on the opposite side of the substrate, the cathode is required to have high transparency and therefore is desirable to have a thickness as thin as possible. However, since resistance value is inversely proportional to thickness, the resistance value of the cathode in the configuration disclosed in Patent Document 1 becomes significantly high by reducing the thickness. Therefore, the reduction in the thickness causes a problem that the electrical conductivity of the light-emitting element is decreased.
The electrical conductivity of the cathode can be enhanced by increasing the ratio of Ag in the MgAg forming the cathode. However, in such a case, there is a possibility that asperities are generated by aggregation of the Ag atoms, and if a layer for absorbing the effect of such asperities is additionally formed, there is a possibility of a change in the light-emitting characteristics.